Abstract

Climate change has significant influences on agricultural water management particularly in arid and semi-arid regions. Increased water scarcity and consecutive droughts in these regions must be extensively taken into considerations in any water management scheme dealing with agricultural production. This study was aimed to find out climate changes impacts on soil water balance components and rainfed wheat yield, phenology and failure across eight different soil textural classes over 2070–2099. In order to project the future conditions, outputs of five climate models under RCP-4.5 and RCP-8.5 downscaled by MarkSimGCM were used to drive the CSM-CERES-Wheat v4.6 model. Results indicated that crop-growing season will be shorter by 10.7–21.6 days under RCP-4.5 and 25.8–45.5 days under RCP-8.5. Averaged across all investigated soils, the crop yield would decline in four studied large areas mainly due to drought and inappropriate planting date. Yield loss, averaged across all sites, are likely to be higher in finer-texture soils. More frequent harvest failure can occur over the 2080s particularly in the finer-textured soils at most studied sites. Deep drainage and runoff are expected to drop in almost all soils due to rainfall deficit. Decline of evaporation appears likely as a consequence of drought, shorter growing period and change of evapotranspiration partitioning. The crop model projected larger reduction in drainage and evaporation for coarse soils and in runoff for finer-textured soils. Higher transpiration, averaged over all sites, in coarser soils can be attributed to considerable decline of nitrogen leaching and higher subsoil water content. Furthermore, there would be an increase in soil water storage under most soil-climate simulation runs particularly in heavy-textured soils. In general, soil texture as an inherent static property highly conditions crop-climate interactions in changing climates. Furthermore, rainfed wheat production would likely be more sustainable on coarser soil textures under climate changes.